/Engine/Plugins/Online/OnlineSubsystem/Source/Public/OnlineSubsystemModule.h
Destroys an online subsystem created internally via access with GetOnlineSubsystem Typically destruction of the subsystem is handled at application exit, but there may be rare instances where the subsystem is destroyed by request
virtual void DestroyOnlineSubsystem ( const [FName](API\Runtime\Core\UObject\FName) InSubsystemName )